skeleton_external.c

/* * Skeleton for a sample external io engine * * Should be compiled with: * * gcc -Wall -O2 -g -shared -rdynamic -fPIC -o engine.o engine.c * */#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <errno.h>#include <assert.h>#include "../fio.h"/* * The core of the module is identical to the ones included with fio, * read those. You cannot use register_ioengine() and unregister_ioengine() * for external modules, they should be gotten through dlsym() *//* * The ->event() hook is called to match an event number with an io_u. * After the core has called ->getevents() and it has returned eg 3, * the ->event() hook must return the 3 events that have completed for * subsequent calls to ->event() with [0-2]. Required. */staticstruct io_u *fio_skeleton_event(struct thread_data *td, int event)
{
return NULL;
}
/* * The ->getevents() hook is used to reap completion events from an async * io engine. It returns the number of completed events since the last call, * which may then be retrieved by calling the ->event() hook with the event * numbers. Required. */staticint fio_skeleton_getevents(struct thread_data *td, unsignedint min,
unsignedint max, struct timespec *t)
{
return 0;
}
/* * The ->cancel() hook attempts to cancel the io_u. Only relevant for * async io engines, and need not be supported. */staticint fio_skeleton_cancel(struct thread_data *td, struct io_u *io_u)
{
return 0;
}
/* * The ->queue() hook is responsible for initiating io on the io_u * being passed in. If the io engine is a synchronous one, io may complete * before ->queue() returns. Required. * * The io engine must transfer in the direction noted by io_u->ddir * to the buffer pointed to by io_u->xfer_buf for as many bytes as * io_u->xfer_buflen. Residual data count may be set in io_u->residual * for a short read/write. */staticint fio_skeleton_queue(struct thread_data *td, struct io_u *io_u)
{
/* * Double sanity check to catch errant write on a readonly setup */
fio_ro_check(td, io_u);
/* * Could return FIO_Q_QUEUED for a queued request, * FIO_Q_COMPLETED for a completed request, and FIO_Q_BUSY * if we could queue no more at this point (you'd have to * define ->commit() to handle that. */return FIO_Q_COMPLETED;
}
/* * The ->prep() function is called for each io_u prior to being submitted * with ->queue(). This hook allows the io engine to perform any * preparatory actions on the io_u, before being submitted. Not required. */staticint fio_skeleton_prep(struct thread_data *td, struct io_u *io_u)
{
return 0;
}
/* * The init function is called once per thread/process, and should set up * any structures that this io engine requires to keep track of io. Not * required. */staticint fio_skeleton_init(struct thread_data *td)
{
return 0;
}
/* * This is paired with the ->init() funtion and is called when a thread is * done doing io. Should tear down anything setup by the ->init() function. * Not required. */staticvoid fio_skeleton_cleanup(struct thread_data *td)
{
}
/* * Hook for opening the given file. Unless the engine has special * needs, it usually just provides generic_file_open() as the handler. */staticint fio_skeleton_open(struct thread_data *td, struct fio_file *f)
{
return generic_file_open(td, f);
}
/* * Hook for closing a file. See fio_skeleton_open(). */staticint fio_skeleton_close(struct thread_data *td, struct fio_file *f)
{
generic_file_close(td, f);
}
/* * Note that the structure is exported, so that fio can get it via * dlsym(..., "ioengine"); */struct ioengine_ops ioengine = {
.name = "engine_name",
.version = FIO_IOOPS_VERSION,
.init = fio_skeleton_init,
.prep = fio_skeleton_prep,
.queue = fio_skeleton_queue,
.cancel = fio_skeleton_cancel,
.getevents = fio_skeleton_getevents,
.event = fio_skeleton_event,
.cleanup = fio_skeleton_cleanup,
.open_file = fio_skeleton_open,
.close_file = fio_skeleton_close,
};